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The mind is adaptive II part 1.docx

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Ashley Waggoner Denton

The mind is adaptive II • What is sleep? Many brain regions are more active during sleep than during wakefulness. During sleep, the brain is still active. Sufficient sleep is important for the memory. • Sleep is an Altered State of consciousness. When you sleep, you are not conscious, but your brain still processes information and, to some extent, remains aware of your environment. When people are awake, their brains neurons are extremely active, as evidenced by short, frequent, desynchronized brain signals known as beta waves. When people close their eyes and relax, brain activity slows and becomes more synchronized a pattern that produces alpha waves. Essentially: Awake beta waves. Right before you sleep alpha waves. Sleep occurs in stages, as evidenced by changes in EEG readings: Alert wakefulness Beta waves Just before sleep Alpha waves Stage 1 Theta waves Stage 2 Sleep spindles & K-complex( L. waves) Stage 3 Delta waves Stage 4 Delta waves In stage one you can be aroused easily. In stage two your breathing slows and you are less affected by external stimulations. Abrupt noises can trigger k-complexes. As people age and sleep lighter, their EEGs show fewer sleep spindles. People still process information in stage 4, as the mind continues to evaluate the environment for potential danger. REM sleep: After about 90 minutes of sleep, a peculiar thing happens. The sleep cycle reverses, returning to stage 3 and then to stage 2. At this point, the EEG suddenly shows a flurry of beta wave activity that usually indicates an awake, alert mind. Rapid eye movements happen in this stage called REM sleep (or paradoxical sleep: stage marked by rapid eye movements, dreaming and paralysis of motor systems.).Some neurons in the brain, especially in the occipital cortex and brain stem regions, are more active during REM sleep than during waking hours. During REM episodes, most of the body’s muscles are paralyzed and the body shows signs of genital arousal. The cycle repeats over the course of the night. Sleep disorders: Insomnia is a disorder characterised by an inability to sleep. Mental health and ability to function are compromised. Chronic insomnia is associated with diminished psychological well-being, including feelings of depression. Some people experience pseudo insomnia, in which they basically dream they are not sleeping. The preferred treatment for insomnia is cognitive-behavioural therapy, which helps people overcome their worries about sleep. Other factors that contribute to insomnia include poor sleeping habits. Sleep apnea is a disorder in which a person stops breathing while asleep. Chronic apnea causes people to have poor sleep, which is associated with daytime fatigue and even problems such as inability to concentrate while driving. Narcolepsy is a sleep disorder in which people fall asleep during waking hours. A person may experience the muscle paralysis that accompanies REM sleep. Evidence suggests that narcolepsy is a genetic condition that affects the neural transmission of a specific neurotransmitter in the hypothalamus. The most widely used treatments are stimulants like modafinil although some researchers suggest that narcolepsy is an autoimmune disorder. The opposite of narcolepsy is REM behaviour disorder, in which the normal paralysis that accompanies REM sleep is disabled so that people act out their dreams while they’re sleeping. Unlike Rem behaviour disorder, sleepwalking is a relatively common behaviour that occurs during stage 4 sleep. Technically called somnambulism, it typically occurs within the first hour or two after falling asleep. How to develop good sleeping habits: - Establish a routine. - Never consume alcohol or caffeine just before going to bed. - Regular exercise will help maintain your sleep cycle. - Do not spend time in your bed reading, eating, or watching television. - Relax, do not worry. - When you cannot fall asleep, get up and do something else. - Do not try to make up for lost sleep by sleeping late the next morning or napping during the day. • Sleep is an adaptive behaviour. Some dolphin species have unihemispherical sleep. In which the cerebral hemisphere take turns sleeping. It used to be assumed that all animals sleep, evidence indicates that some animals never exhibit a state that can be considered sleep. Three general explanations for sleep’s adaptiveness: restoration, circadian cycles, and facilitation of learning. Restoration and sleep deprivation: The restorative theory states that sleep allows the brain and body to rest and to repair themselves. Sleep apparently allows the brain to replenish glycogen stores and strengthen the immune system. In a brain imaging study, sleep-deprived people showed increased activation of the prefrontal cortex, which suggests that some bra
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